- update to 2.2.4:
* Only very small code and documentation fixes, hopefully
really the last fix release of the stable branch 2.2, before
the development effort for v2.4 starts.

- update to 2.2.3:
* Only small code and documentation fixes and additions,
probably the last fix release of the stable branch 2.2,
before the development effort for v2.4 starts.
* That's embarrassing but the last version still had a glitch
and the sdist package `rdiff-backup-2.2.2.tar.gz` didn't
contain the pre-rendered man-pages which some packagers
requested.